XXVj BOTRYOPTERIS 437 



Botryopteris forensis Renault i. Figs. 309, B ; 319, D— G. 



The stem of this species from the Upper Carboniferous of 

 St Etienne is 1-7 om. x 7-5 mm. in diameter. The solid stele 

 consists of reticulate tracheae with the smallest elements on 

 the outer edge. The comparatively broad cortex of the type- 

 specimen is traversed by a leaf-trace in an almost vertical 

 course and by vascular strands passing horizontally to roots. 

 The petioles are circular in section and their vascular strand 

 has the form of an eo in transverse section (fig. 319, G), the 

 three projecting arms pointing to the axis of the stem. Both 

 stem and leaves bore large multicellular hairs, spoken of by 

 Renault as equisetiform because of the finely toothed sheaths 

 of which they are composed. The compound fronds had fleshy 

 lobed pinnules with dichotomously branched veins (fig. 309, B) ; 

 stomata are said to be confined to the upper surface, an 

 observation which leads Renault to describe the plant as 

 aquatic on evidence which is hardly convincing. 



The pyriform and pedicellate sporangia are borne in groups 

 of two to six on the ultimate divisions of the frond; the 

 wall is composed of two layers of cells and on one side of the 

 sporangium is an annulus several cells in breadth (fig. 319, 

 D, F). An interesting type of sporangium described by Oliver^ 

 from Grand'Croix in France may, as he suggests, belong to 

 Botryopteris forensis ; the diflferences between Renault's and 

 Oliver's specimens being the result of the more perfect preser- 

 vation of the tissues in the latter. The sporangium described 

 by the English author is circular in section and measures 

 0'65 X 0'53 mm. ; the wall is in part composed of a single layer 

 of cells and in part of two to three layers, a character recalling 

 the '' annulate " sporangia of Botryopteris. Between the spore- 

 mass and the wall is an interrupted ring of short tracheal 

 elements similar to the xylem-mantle which occurs at the 

 periphery of the nucellus of certain Palaeozoic gymnospermous 

 seeds. In the absence of proof of a connexion between this 

 sporangium and Botryopteris it is convenient to use the 

 generic name Tracheotheca subsequently proposed by Oliver'. 



1 Benault (75) ; (96) A. p. 47, PI. xxxii. 



2 Oliver (02). ^ Oliver (04) p. 395 (footnote). 



